GB2223748A

GB2223748A - Closures

Info

Publication number: GB2223748A
Application number: GB8919821A
Authority: GB
Inventors: Nigel Thompson
Original assignee: Metal Closures Ltd; MCG Closures Ltd
Current assignee: Arconic Closure Systems International UK Ltd
Priority date: 1988-09-09
Filing date: 1989-09-01
Publication date: 1990-04-18
Also published as: GB8919821D0

Abstract

A moulded closure has a tamper-evident ring 13 connected to the bottom edge of a skirt 11 by frangible bridges 14. Ring 13 has circumferentially spaced upward protrusions 17 which are inclined inwardly and which may be accommodated within slots 18 in the bottom edge of the skirt. The outwardly facing surfaces of the ring 13, including the protrusions preferably have a substantial upward inclination to enable them to be moulded by an annular mould part (37 Fig 5) from which the ring can be disengaged by a relative axial movement of the ring and mould part. <IMAGE>

Description

IMPROVEMENTS RELATING TO CLOSURES AND CLOSURE MOULDING APPARATUS This invention relates to the manufacture of closures, more particularly screw-threaded closures of the kind having a tamper-evident ring connected to the skirt of the closure by a plurality of frangible bridges.

According to this invention in one aspect there is provided a closure moulded from a resilient plastics material and comprising a top, an annular skirt depending from the top and a tamper-evident ring depending from and connected to the lower edge of the skirt by a plurality of frangible bridges, the ring having a plurality of circumferentially spaced protrusions inclined upwardly and inwardly towards the central axis of the closure and extending into axially overlapping relationship with slots in the lower edge portion of the skirt, which slots are capable of accommodating said protrusions.

According to a preferred feature of the invention, the surfaces of the ring and bridges which are disposed radially outward of the general internal profile of the ring and which face in a direction having a component parallel to the central axis of the closure and towards the top have also a substantial radially outwardly facing component.

According to another preferred feature of the invention the surfaces of the protrusions facing towards the top have portions inclined radially inwardly at a greater angle than other portions thereof.

The invention also provides for use in the manufacture of a closure as described in the preceding paragraph moulding apparatus comprising a core member of generally cylindrical form, a second member enveloping one end portion of the core member so as to define therewith a cavity in the shape of the top and skirt of the closure down to but excluding the bottom edge of the skirt, a third member including a body which extends about the core member and abuts the bottom edge of the second member and which has mounted thereon, for swivelling movement about respective axes extending tangentially of the skirt and disposed below the bottom edge of said ring, a plurality of axially-extending arms the end portions of which nearer the top define the slots in the bottom edge of the skirt and which define also the radially outwardly-facing surfaces of the protrusions and the radially outwardly-facing surfaces and bottom edges of the parts of the ring axially aligned with the slots, the body of the third member defining the bottom edge of the skirt between the slots and the outwardly facing surfaces of the bridges and the outwardly facing surfaces and bottom edge of the ring between the arms, and said core member having mounted in axial grooves therein a plurality of fingers which are axially slidable in the grooves said fingers having a circumferential extent equal to said (first) surface portions of the protrusions having said greater angle of inclination and being adapted to shape these surface portions and the parts of the radially inwardly facing surfaces of the protrusions and the ring axially aligned with said first surface portions, said other portions of said surfaces of the protrusions being defined by the core member, and means whereby axial movement of the fingers in a direction away from the top of the closure causes the arms to pivot outward about their pivot axes to enable the protrusions to be pivoted outward into the slots by the cam action of the fingers against said first surface portions.

The invention will now be described in more detail with reference by way of example to the accompanying drawings in which: Figure 1 is a side elevation of a closure according to the invention, partly in section on the line 1-1 of Figure 2, Figure 2 is a fragmentary underneath view in the direction of the arrow 2 of Figure 1, partly in section on the line 2-2 of Figure 1, Figures 3 and 4 are respectively sectional views on the lines 3-3 and 4-4 of Figure 2, and Figure 5 is a fragmentary diagrammatic axial section of a moulding apparatus according to the invention.

Referring to Figures 1 to 4 ofthe drawings, the closure comprises a top 10, an annular skirt 11 formed with a screw-thread 12 on its inner surface, and a tamper-evident ring 13 depending from and connected to the lower edge of the skirt by frangible bridges 14 extending across a circumferentially-extending axial gap 15 between the ring and the skirt. Evenly spaced about the circumference of the upper edge of the ring are a number of protrusions 17 which are inclined upwardly and inwardly towards the central axis of the closure and which project into respective rectangular notches 18 formed in the bottom edge portion of the skirt, with gaps between the peripheries of the protrusions and the notches.Circumferential gaps 19 between the sides of the protrusions and the sides of the notches limit the degree of relative rotation of the ring 13. and the upper portions of the closure during application of the closure to a container and during at least part of the movement to unscrew the closure.

The surfaces of the protrusions 17 which face the top 10 are inclined radially inwardly, the circumferentially inner portions 21 being inclined at a greater angle than the flan-king portions 22.

All of the surfaces of the ring which are disposed radially outward of the general internal profile of the ring and that face in a direction having a component which both is parallel to the central axis 20 and faces towards the top 10 have a substantial radially outwardly facing component. In the present instance the general internal profile of the ring is a cylinder of radius R. Thus, the portions 24 of the radially outer face of the ring between the bridges and protrusions are inclined outwardly and upwardly at an angle which in the 0 illustrated construction is approximately 40 to the horizontal, and at the locations of the bridges the outer surfaces 25 of the ring are inclined outwardly and 0 upwardly at an angle of approximately 70 to the horizontal.In addition, the radially outer surfaces 26 of the protrusions are inclined upwardly at an angle of 0 approximately 70 to the horizontal. The portions 24 of the outer face of the ring intersect the radially inner face of the ring below the bottom edge of the skirt to form the circumferentially-extending axial gap 15, interrupted by the bridges 14. The bottom outer edges 28, 29 of the outer surfaces 24 and 25 form a smooth continuation of each other. The bottom outer edges 30 of the protrusions however project outward beyond the edges 28, 29. The outward inclination of all the aforesaid surfaces of the ring which are outward of the cylinder of radius R is advantageous in that in the moulding of the closure the said surfaces can be formed by mould components from which the moulded closure can be extracted by a simple axial relative movement after the other mould parts, and primarily an internal core mould part, have been removed.

During application of the closure to the neck of a bottle or other container having an external screwthread and a security band below the screw-thread, the slightly inclined inner surfaces 17a of the protrusions 17 come into engagement with the security band and cause the protrusions to hinge outward about their lower ends into the notches 18, allowing ring 13 to pass over the band.

When the closure is unscrewed, the upper end surfaces 22 of the protrusions come into abutment with the bottom shoulder of the security band and continued unscrewing causes the bridges to fracture. The ring 13 is thus separated from the upper portions of the closure and shows that the closure has been removed or has been tampered with.

In some arrangements one or more of the frangible bridges 14 may be replaced by wider, stronger bridges and in this case vertical or axial lines of weakening are scored on the radially outer surface of the ring 13 adjacent the wider bridges. This arrangement permits the tamper-evident ring to be removed from the container with the upper parts of the closure.

The upper ends of some of the protrusions 17 may be differently spaced from the bottom edge of the ring 13 to others of the protrusions, so that the upper ends of the protrusions do not all simultaneously come into engagement with the security band. For example the upper ends of four of the protrusions angularly spaced 0 apart by 90 may be a first distance from the bottom edge of the ring and the upper ends of the four intermediate protrusions may be a lesser distance from the bottom edge of the ring.

Referring now to Figure 5 of the drawings, a moulding apparatus is illustrated which is advantageous in enabling the closure of Figures 1 to 4 to be moulded without using split mould members. A core member 35 shapes the whole of the radially inner surface of the closure, and an upper mould member 36 shapes the external surfaces of the closure down to but excluding the gap 15.

The radially outer surfaces of ring 13 and protrusions 17, the gaps 15 and 19 are formed by a mould sleeve which incorporates outwardly hinging levers.

In the illustrated construction, gap 15, the bottom end of the skirt, and the outer surfaces of ring 13 and bridges 14 are formed by a mould sleeve 37. The radially outer surfaces of protrusions 17, and gaps 19 which describe notches 18, are formed by levers 38 of circumferential width equal to the width of the notches 18. The levers 38 are located in axial slots in the mould sleeve 37 and are individually pivoted about tangential hinge points 39 on the lower end of the mould sleeve 37. At a location above the hinge points 39, a garter spring 40 extends about the levers, urging them radially inwards so that their upper, inner surfaces complete the mould form at the radially outer surface of the protrusions 17, and the notches 18. The spring holds the levers in position during moulding of the closure.

The protrusions 17 have their radially inwardly facing surfaces 21 formed by respective fingers 41 which are axially slidably located in axial slots in the radially outer surface of the mould core member 35.

During filling of the mould cavity, these fingers are held in their upper end positions in the slots. The fingers are disposed radially opposite the respective hinged levers in the outer mould sleeve, and have a circumferential extent equal to that of the surfaces 21.

To extract the closure from the mould, the upper mould member 36 is first withdrawn upward. The fingers 41 in the mould core 35 are then moved downward independently of the core and guided by the slots in the core. Cam surfaces 43 on the outer edge of the fingers engage with mating cam surfaces 44 on the inner edge of the hinged levers 38 causing the levers to hinge outward. Simultaneously, a cam action takes place between the circumferentially inner surface portions 21 of the protrusions 17 and the complementary surfaces of the fingers 41 causing the protrusions 17 to be pivoted outward about their lower ends into the spaces vacated by the hinged levers 38. The cam action between fingers 41 and hinged levers 38 produces, for a given axial displacement of the fingers 41, a greater radial displacement of the upper ends of the levers than of the protrusions, due to the fact that the angle of inclination of surfaces 21 to the central axis 20 of the closure is less than that of the cam surfaces 43, 44. Thus, the levers vacate the spaces before the protrusions 17 pivot outward during continual axial downward movement of the fingers.

The core member can then be withdrawn downward, "jumping" the screw threads 12, without damage to the protrusions 17 or to the bridges 14.

Finally, a central push rod (not shown) is moved upward through the centre of the core to remove the moulded closure from the mould sleeve 37.

Claims

1. A closure moulded from a resilient plastics material and comprising a top, an annular skirt depending from the top and a tamper-evident ring depending from and connected to the lower edge of the skirt by a plurality of frangible bridges, the ring having a plurality of circumferentially spaced protrusions inclined upwardly and inwardly towards the central axis of the closure and extending into axially overlapping relationship with slots in the lower edge portion of the skirt, which slots are capable of accommodating said protrusions.

2. A closure as claimed in claim 1, wherein the surfaces of the ring and bridges which are disposed radially outward of the general internal profile of the ring and which face in a direction having a component parallel to the central axis of the closure and towards the top have also a substantial radially outwardly facing component.

3. A closure as claimed in claim 1 or claim 2, wherein the surfaces of the protrusions facing towards the top have portions inclined radially inwardly at a greater angle than other portions thereof.

4. Moulding apparatus for moulding a closure as claimed in claim 3, comprising a core member of generally cylindrical form, a second member enveloping one end portion of the core member so as to define therewith a cavity in the shape of the top and skirt of the closure down to but excluding the bottom edge of the skirt, a third member including a body which extends about the core member and abuts the bottom edge of the second member and which has mounted thereon, for swivelling movement about respective axes extending tangentially of the skirt and disposed below the bottom edge of said ring, a plurality of axially-extending arms the end portions of which nearer the top define the slots in the bottom edge of the skirt and which define also the radially outwardly-facing surfaces of the protrusions and the radially outwardlyfacing surfaces and bottom edges of the parts of the ring axially aligned with the slots, the body of the third member defining the bottom edge of the skirt between the slots and the outwardly facing surfaces of the bridges and the outwardly facing surfaces and bottom edge of the ring between the arms, and said core member having mounted in axial grooves therein a plurality of fingers which are axially slidable in the grooves said fingers having a circumferential extent equal to said (first) surface portions of the protrusions having said greater angle of inclination and being adapted to shape these surface portions and the parts of the radially inwardly facing surfaces of the protrusions and the ring axially aligned with said first surface portions, said other portions of said surfaces of the protrusions being defined by the core member, and means whereby axial movement of the fingers in a direction away from the top of the closure causes the arms to pivot outward about their pivot axes to enable the protrusions to be pivoted outward into the slots by the cam action of the fingers against said first surface portions.

5. A closure substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

6. Moulding apparatus substantially as hereinbefore described with reference to and as illustrated in Figure 5 of the accompanying drawings.